1. Field of the Invention
The present invention relates to a method and apparatus for selecting a network in a communication system. More particularly, the present invention relates to a method and apparatus for simultaneously searching for a plurality of networks and selecting a network.
2. Description of the Related Art
Mobile communication protocols have advanced from 2nd Generation (2G) and 3rd Generation (3G) technologies and are now focused on 4th Generation (4G) technologies. Each generation of technology is distinguished based on a data transmission rate. Eurocentric asynchronous scheme-based communication technology and US centric synchronous scheme-based communication technology have continued in parallel until 3G. In 4G, an asynchronous-scheme based Long-Term Evolution (LTE) has become an unparalleled communication technology. Although the LTE technology has already been commonly used in several countries such as the U.S., Korea, and the like, it is not in widespread use. Accordingly, in an area where the LTE is not commonly used, mobile communication is supported by 2G or 3G communication technologies.
When a call is made in a Circuit Switched (CS) domain, an exclusive one-to-one physical route is established between a sender and a receiver and is maintained until the call is finished. Accordingly, because a connection is continuously maintained, a stable service is provided and delays occur infrequently.
Conversely, in a Packet Switched (PS) domain, data is bound based on a packet unit and a physical route is only connected between a sender and a receiver when a packet is to be transmitted. When there is no packet to be transmitted, the connection is released until data is generated again. Therefore, because network resources are consumed only when the data transmission is required, a network system may more effectively manage resources. However, a delay may occur more frequently in the PS domain when compared to the CS domain.
The LTE technology supports the PS domain but does not support the CS domain. Since the LTE technology does not support the CS domain, the LTE technology requires a mobile-Voice over Internet Protocol (mVoIP) technology such as Voice over LTE (VoLTE) to provide voice communication. However, a technical problem in mobility currently remains in the LTE technology. Therefore, various technologies have been proposed to support voice communication in the LTE network. Simultaneous Voice and LTE (SVLTE), which is an example of a proposed technology, is introduced by communication companies which have provided Code Division Multiple Access (CDMA) 2000 1×RTT and EV-DO as the 3G communication technology.
The SVLTE technology refers to a technology that provides voice communication through a CDMA2000 1×RTT network and provides data communication through an LTE network. That is, it enables data transmission and reception through an LTE network while voice communication is provided through a CDMA network. To support this, a mobile station uses a plurality of Radio Frequency (RF) modules, for example, 2 RF modules. That is, one RF module is used for the voice communication and the other RF module is used for the data communication.
However, there are not many areas where the LTE technology has been commonly used. Also, a mobile station that supports the LTE technology for overseas roaming service needs to perform communication with a 2G or 3G network in an area where the LTE network does not exist. A mode in which a mobile station supports a plurality of communication protocols corresponds to a global mode. In the corresponding mode, the mobile station selects a network system based on a predetermined priority and attempts to obtain the network system. In general, a mobile station that supports the SVLTE uses a priority of an MMSS Location Associated Priority List (MSPL) defined in the 3GPP2 C.S0016-D standard. The MSPL is a list indicating a priority of a network system that a mobile station attempts to obtain based on a national code and a network code of an area in which the mobile station is located. The mobile station attempts to obtain the network system based on the priority. Here, the priority is determined based on a combination of a home communication business operator, a roaming communication business operator, and a type of a network system. Generally, the home communication business operator has a relatively higher priority, and the latest communication technology has a higher priority than a previous communication technology when the communication company is the same. Generally, the roaming communication business operator has a lower priority than the home communication business operator in the MSPL, and a mobile station searches for a home system in a roaming area, and then searches for another network system. Therefore, in the roaming area, the mobile station expends a great amount of time to search for a network and thus establishing communication is delayed and performance of an overall communication system is deteriorated.
Therefore, a need exists for a system and method for selecting a network in a communication system.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.